Permission to conduct this research was given by the Ministry of Higher Education and Scientific Research in the Cameroon. We are grateful to the Leverhulme Trust (D.M.N., during the tenure of a Research Fellowship) and Carnegie Trust (I.J.A.) for financial support. S. J. Gardiner undertook the chemical analyses of the 1984 and 1986 samples at Stirling, and F. Namata helped invaluably in the field. We are grateful also for the assistance afforded us by British Embassy and the British Council in Yaoundé, and Plantations Pamol du Cameroun Limited. Full acknowledgements for the original enumeration study and soil sampling are given in Gartlan et at. (1986).

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